Preparation of basic barium sulfonates in a non-volatile solvent



l RE P ARATION F BASIC BARIUM SULFONATES "IN a NDN-VOLATILE SOLVENT Paul C. Kemp and Roy C. Sias, Ponca City, Okla., as-

signors to Continental Oil Company, Ponca City, Okla., .a corporation of Delaware No Drawing. E iled-Qct. 13, 19.58,:Ser. No. 766,655 12 Claims. (Cl. 252-18) Il 1e present invention relates to basic barium sulfo- .nates as additives for lubricating oils. More particularly,

the present invention relates to an improved process for' preparing barium sulfonatesofhigh excess basicity.

The use ofbarium sulfonates as additive agents in lubricating oils is well known." Theyfunction as dispersants for the decomposition products and prevent, or minimize, the deposition offiarnish'dn the piston skirts, upon the rings, andin the ring grooves. The use ofbasic barium sulfonates is also .well known. By basic metal salt is meant one that contains '.an.amount of metal in excess of that theoretically requiredlto replacefthe acidic hydrogens .of; the.su1fonic.acid. "The presence of suchbasicity neutralizes the 'acidicfcornbustionproducts, thereby counteracting any potential deleterious .efiect. The combination Lo-f these Ltwo function lca'u ses'basiesbarium .s'ulfonzi'tes to b e.very.desirable additive'sjfor lubricating 115:

The preparation. of basic barium s'ulfonate's.is...alsowell known. For-example, Asse'ff et al.ii1.U.S. 2,616,924 dis? "closelthe preparation of dispersions otbarium'hydroxide finoil by heating together an oil solution ofja. barium isulfonatean aqueous' ba rium oxide slurry, and a phenol and removing the water by "heating at 150 C. The

phenol in this process functions as a .promoter'.

Another process f or the preparation of basic barium sulfonatesis that.disclosed by Mertes in U.S. 2,501,732.

,ln'v this processasolution or slurry of the desired base is .addedwith' stirringto thedesired oil-soluble metalsulforiate. The reaction massis then dehydrated by heating to temperatures of between 150 and 500 F., preferably between 200 and 450 F. If temperatures below 250 ":F. are used, itmaylbenecessaryl to .use. a vacuum in order to efiect .eompletesremoval. of the water. The product is filter.ed tolemove .unreactedbase or other material which has .nOt ,been solubilized .during the treatment.

In ,gener al, one or more of the following difficulties are present in the processes of the prior art:

(1) Low excess basic'it'y," i (2,) The formationpf a.gelatinous, difiicultly filterable ,product, I (3) Low utilization of barium,

. .(4){ Formation emulsions which are difiicult to handle.

The present inventionflobviates the difficulties encounterediin' thefpri or art and provides a convenient and economical process for, the 'prepar'ationfof basic. barium sulfonates. Further, the present, invention provides a proc- .esslwhich does not possess gel-forming or filtration .difii- Bulties'." Still further,".the pr eserit invention provides a process which has a,' h igh utilizationof barium.

.Broadly stated, jthe proces's of }the present invention .CQmP thefo lo-wingz (a) gFo'rmin'g a solution of oibsolublesulfonic acid and nonggvolatile solventiina volatile aromatic solvent; ((12) Adding a hotaqueous solution of barium hydro to: the solution of oil soluble sulfonic, acid;

(c) Heat1' 'g the reaction mixture to reflux, temperature td efle'ct complete re'actionj United States Patent-O fiatented May 2, 1961 ,2 (d) Removing substantially all of the water by means of azeotropic distillation "with volatile aromatic solvent; (e) Removing any residual volatile aromatic solvent by distillation; v j I (f) Finalstripping the product by blowing with a chemicallyinertgas and then filtering the product.

Any of the sulfonic jacidsnormally used in the manufacture of lubricating oil additives may be used in this process. Examples of these materials'would include mahogany sulfonic acid, diwaxi-benzene sulfonic acid, dinonylnaphthal'ene sulfonic acijd,1and' post'dodecylbenzene sulfonic acid. The preferred material is postdodecylbenzene sulfonic acid. .Bostdodecylbenzenei's aby-product of the ma nufactureof dodecylbenzene, being the material distilling above .dodecylbenzene. Sometimes, in Order to improve oil solubility, the lower boiling materials are removed by distillatiomjand the product is then v known as stripped postdodecylbenzene.

.Postdodecylbenzene consistsof monoalkylbenzenes and Viscosity. at

.The purpose of the non volatile solvent, or, as other- Wise'kpow'n, 'carrier fluid, is to adjust the concentration of the sulfonate in thefinal pro'duct. The solvent should be relativelyliighboiling,that is above 150 C. Because of availability price;petroleumhydrocarbons of suit- ;able boilingrange are; preferred. More particularly, the "preferred materialis aparaifinic lubricating oil havingan SSU'viscosity 100 FQoff ab tlpfo.

The volatile aromatic ,solvent shopld, for economic reasons, be onewhich' yields in relatively small propor- "tiori's an azeotrope with water, and which has a relatively low "boiling: point. I d d 'thoughbe'nzene and xylene maybe used.

oluene is t e preferred material, al-

" Therelative amounts of sulfonic acid, non-vol til l. vent, and'fvolatile aromatic solvents to be used are as followsir. "J V Component Suitable Preferred Wt. Percent) (Wt. 1?ercent) Sulfonie acid"; 15-55 20-28 Non-volatile solve 15 35 18-23 Volatile aromatie solveut i 30:70 50-60 The aqueous solutio ri o f barium hydroxide to be used is prepared by addingbarium oxide, barium hydroxide,

Iarid the various. hydrates of barium hydroxide to water,

or ,vice ,versa'. ,A hot (--100 C.) aqueous solutionis employed. The solution should either be gravity settled tor' sseveral hourszor filtered in order to remove insoluble material; 'Su'ificientwatershould be used to insure compls fiilizst e ib f il ilfi il som oy Th acceptable amount of water is between 20 and 100 percent (by weight) of the acid mixture, while the preferred amount is between 30 and 50 percent (by weight), including any water of hydration. The amount of barium hydroxide employed is from 1 to 2% times that required to react with the sulfonic acid. The utilization of barium by this process is very high, being 90 percent .or better.

The neutralization and over-basing reaction are carried out at reflux temperature (about 85 C.). The time required is negligible. being anything from 5 to 60 minutes, with to 30 minutes being preferred. Preferably, sufficient water-soluble barium compound is added at this stage to provide the desired excess basicity. Alternatively, the neutralization and over-basing may be done in two steps, in which case the most of the water present in step one is removed before proceeding to step two.

The use of a volatile aromatic solvent to form an azeotrope with water is a salient feature of this invention. This practice results in essentially eliminating any gelation problem. The amount of solvent used is not critical; however the temperature used is critical. As stated previously, the reaction mass should not be heated above 135 C., preferably not above 115 to 120 C., until water has been completely eliminated. The azeotrope step may be practiced in a variety of ways. For example, one method is to remove all of the water in a one-step operation by.

adding large amounts of toluene. Alternatively, less toluene may be used if the azeotropic vapor is condensed and the toluene layer continuously recycled to the reaction mass. In such case. the water layer formed on azeotrope condensation is reiected by a conventional trap.

A third and convenient laboratory method is to (1) remove considerable water by distilling the product to a maximum pot temperature of 135 C. (preferably 1l5- 120 C.),' (2) cool to permit the addition of more volatile' aromatic solvent without excessive loss by fiashing,.

and (3) removal of the last traces of water by redistillation.

The product is then stripped by blowing with an inert gas and then filteredthrough a filter aid. for example, Hyflo. ing With carbon dioxide. in which case the barium compound is converted to the carbonate, the degree of conversion being dependent on the amount of blowing. These steps'are well known in the art.

In order to disclose the nature of the present inventionstill more clearly. the following illustrative examples will.

be given. It is to be understood that the invention is not to be limited to the specific conditions or details set forth in these examples except in so far as such limitations are specified in the appended claims.

If desired. the product may be stripped by blow- 'fonate was settled at 50 C. for 48 hours.

of Ba(OI-I) -8H O dissolved in 150 milliliters of hot water (90 C.). After complete neutralization, the sul- The aqueous layer was removed by means of a separatory funnel, and 300 grams of the sulfonate (52.8% toluene) was overbased by adding 31 grams of Ba(OH) -8l-I- 0 dissolved 1n 60 milliliters of water. The reaction mixture was refluxed (85 C.) for 15 minutes, after which the toluene and most of the water were removed by heating to a pot tem- In these examp es the acetic base numbers were deter- I minedby the acetic titration method which utilizes glacial 1 acetic acid as the solvent and a solution of perchloric acid in glacial acetic acid asthe titrant. The method is especially adapted for determinations of this type, since equilibria are obtained rapidly. The procedure for carrying out acetic acid titrations is generally outlined in Analytical Chemistry, volume 23, No. 2, February 1951, page'337, and volume 24, No. 3, March 1952, page 519.

ASTM base numbers were determined using ASTM procedure D664-54 and by means of a precision automatic titrator.

The expression PDB" refers to postdodecylbenzene.

EXAMPLE I The starting material was a crude PDB sulfonic acid which had a total acidity of 2.22 milliequivalents per gram and a sulfonic acidity of 1.19 milliequivalents per gram. Five hundred grams of this crude PDB sulfonic acid was treated with 19 grams of lime, diluted with 680 milliliters of toluene, and then filtered. To the toluene solution of purified sulfonic acid was added 93.5 grams 'move' organic solvent and water.

perature of 120 C. The reactants were cooled to about 100 C., 150 milliliters of toluene were added, and the remainder of the water removed by azeotropic distillation. The reactants were then blown with nitrogen at 150 C. for 15 minutes, followed by filtration through Hyflo. 'The product had the following analysis:

Base number (acetic) 67 Base number (ASTM) 61 Percent barium (weight) 13.0

Percent sulfonate (weight) 46.0

EXAMPLE II A pilot plant batch of basic barium sulfonate was prepared in the following manner:

Equipment: 30-gallon Pfaudler kettle. Composition of PDB sulfonic acid solution:

Percent toluene 56.2. Percent diluent oil 21.9. Percent sulfonic acid 21.9. Total acidity 0.452 milliequivalent/gram. Sulfonic acidity 0.449 milliequivalent/gram.

One hundred thirtyfpounds of the PDB sulfonic acid was charged to the kettle. To this was added 24.0 pounds of commercial Ba(OH) -8H O dissolved in 36.7 pounds of hot water (90 C.). The Ba(OH) solution had been settled overnight at about 90 C. to remove water-insoluble material before charging to the Pfaudler kettle. The reactants were agitated for one hour, while maintaining the temperature at 85 C., then heated to 120 C. to re- The reactants were cooledto 100 C., 5 gallons of toluene was added, and the remainder of the water was removed from the reaction mass by azeotropic distillation. The reactants were then blown with nitrogen for two hours at 150 C. Following this. they were slurried with 0.7 pound of Hyflo and then filtered twice through Hyflo. The product had the following analysis:

Base number (acetic) 69 Base number (ASTM) 71 Percent barium (weight) 14.9 1 Percent sulfur (weight) 2.91 Percent barium sulfonate (weight) 46.3

EXAMPLE III The PDB sulfonicacid used here was the same as used in Example II. Three hundred grams of this PDB sulfonic acid solution was charged to a reaction flask and heated to 80 C. A solution was prepared containing 53 grams of Ba(OH) -8H O in 100 milliliters of water,

' heated to 85-90 C., filtered and then added to the sulfonic acid solution. The reaction mixture was heated at reflux temperature for 30 minutes, after which the toluene and most of the water were removed by heating to a pot temperature of C. The reaction mass was cooled to I EXAM-PLE-IV I In .this example the process disclosedin U.S. Patent 2,501,73 1- to Mertes was followed. Specific details of the .process were as follows: .One hundred fifty grams of a barium PDB sulf onate (41.0 wt. percent Ba sulfonate) was charged to .a one- .liter, three-necked flask equipped with athermometer product are shown in the table.

" EXAMPLE V The PDB sulfonic acid used in this preparation had the following analysis:

Percent toluene 51.6. Percent diluent oil .l 23.6. Percent sulfonic acid 24.8. Total acidity 0.47 milliequivalent/gram. Sulfonic acidity 0.52 milliequivalent/gram.

Three thousand grams of the PDB sulfonic acid solution was charged to a 12-liter, three-necked reaction flask. An aqueous solution of barium hydroxide was prepared by dissolving 340 grams of commercial barium oxide (analysis88.5 percent (weight) of BaO) in 1,600 grams of water. The solution was heated to 90 C. and filtered into the reaction flask. The reaction was heated at reflux temperature for 90 minutes, after which the toluene and most of the water were removed by heating to a pot temperature of 125 C. The reaction mass was cooled to about 100 C., whereupon 300 milliliters of toluene was added to the reaction flask. The remainder 'of the water was removed by az eotropic distillation. The

Sufficient barium was charged to theoretically yield a 74 base number product. Based on the 69 acetic base number product, a barium utilization of 93.2 percent was obtained in this preparation.

EXAMPLE VI The procedure of Example I was followed with the exception that benzene was employed as the solvent instead of toluene. In the overbasing step, the reaction mixture was refluxed at about 70 C., the water and benzene were removed to a pot temperature of 110 C., and the reaction mixture was then cooled to about 85 C. prior to the addition of the benzene. Product analysis was as follows:

Base number (acetic) 69 Base number (ASTM) 62 Percent barium (weight) 13.05

Percent sulfonate (weight) 46.0

EXAMPLE VII The procedure of Example I was followed with the exception that petroleum xylene, which is a mixture of .the three isomers of xylene plus some ethyl benzene, was employed as the solvent instead of toluene. In the overbasing1step, the :reaction .mixture .wasirefluxed ;at 5.3130111:

90 C. Final solvent stripping was accomplished by the application of house vacuum at 150? C. "for about 15.

minutes. Product analysis was as followsz To a three-necked, one-liter flask was charged 71.3 grams of a mahogany sulfonic acid (800 weight percent active, combining weight 430), 39.1 grams of 100 pale oil having a viscosity of'100-SSU at 100"F., and- 150 milliliters of toluene. After mixing, a hot (90C.) solution of aqueous Ba(QH) ,comprising 46.5 grams of dissolved .in" 125 milliliters of-water was :filtered into the reactionmass. Heat '.was tthen; applied, sandrthe reaction mass was refluxed (85 C.) for about 15 minutes. Then Water and solvent were removed to a pot temperature of 110 C., whereupon 150 milliliters of toluene was charged to the reaction mass, and the residual water was removed by azeotropic distillation. The solvent was then removed from the reaction mass by heating the reaction mass to a pot temperature of 150 C., followed by stripping with gaseous nitrogen for about 15 minutes at that temperature. The reactionmass was then filtered through Hyflo to yield a bright, fluid product which had a base number (acetic) of 64. 1

The examples have shown a convenient and economical process for the preparation of barium sulfonates of high excess basicity. The data presentedin Example V indicate that the process of this invention provides a high utilization of barium. In addition, the formation of difiicultly filterable gels is quite negligible in the process of the present invention. The process used in Example IV is representative of the prior art. The data presented in the table clearly indicate the superiority of the present I process.

Table PRODUCT COMPARISON-EXAMPLES III AND IV Product Data Example III Example IV B se number (acetic) 81 27 Filtration time (minutes) 44 240 Filtration rate (gram/minute) 2. 27 0. 416 Appearance Bright Hazy While particular embodiments of the invention have been described, it will be understood, of course, that the invention is not limited thereto, since many modifications may be made; and it is, therefore, contemplated to cover by the appended claims any such modifications as fall within the true spirit and scope of the invention.

The invention having thus been described, what is claimed and desired to be secured by Letters Patent is:

1. A process for preparing a dispersion of a barium hydroxide in a barium salt of an oil-soluble sulfonic acid, said process comprising the following steps:

(a) dissolving a mixture of 15 to 35 parts of oilsoluble sulfonic acid and 15 to 35 parts of non-volatile solvent in 30 to 70 parts of a volatile aromatic hydrocarbon solvent selected from the group consisting of toluene, benzene, and xylene,

(1)) adding a hot aqueous solution of barium hydroxide to the solution of oil-soluble sulfonic acid, said solution of barium hydroxide containing from about 1 /2 to about 2 /2 times the amount of barium hydroxide required to react with the sulfonic acid,

(0) heating the reaction mixture at reflux temperatures,

.(d) removing substantially all of the water by azcoamatic solvent is xylene.

tropic distillation with the volatile aromatic hydrocarf bon solvent,

te) removing any residual vvolatile aromatic solvent by distillation,

(f) stripping and filtering the product.

2. The processof claim 1, wherein the oil-soluble sul- 'fo'nieacid is postdodecylbenzene 'sulfonic acid. 5v: 3. The process of claim 1, wherein the oil-soluble sulfonic acid is a mahogany sulfonic acid.

4. The process of claim 1, wherein the volatile aro- Tmatic solvent is toluene.

5. The process of claim 1,: wherein the volatile aromatic solvent is benzene 1 1 8. The process of claim 1, wherein the addition of barium hydrox de in step (b) is conducted as a two-step 'matic solvent is toluene.

operation, the first beingv a neutralization step and the second being an overbasing step, wherein the total amount of barium hydroxide used is'from 1 /2 to 2 /2 times that required to' react with the 'sulfonicacid.

9. The processof claim 2, wherein the non-volatile solvent is a paraffinic lubricating oil having an SSU viscosity at 100 F. of about 100. r

1 0;The process of claim 3, wherein the non-volatile vsolvent 'is' a paraflinic lubricating oil having an SSU viscosity at 100 F. of about 100.

ll. The process of claim 9, wherein the-volatile aromatic solvent is toluene.

12." The process 'of claim 11, wherein the volatile aro- References Cited in the file of this patent UNITED STATES PATENTS 2,739,125 Myers etal. -Q. Mar, 20', 1956 2,779,784 Sharrah Jan. 29, 1 957 

1. A PROCESS FOR PREPARING A DISPERSION OF A BARIUM HYDROXIDE IN A BARIUM SALT OF AN OIL-SOLUBLE SULFONIC ACID, SAID PROCESS COMPRISING THE FOLLOWING STEPS: (A) DISSOLVING A MIXTURE OF 15 TO 35 PARTS OF OILSOLUBLE SULFONIC ACID AND 15 TO 35 PARTS OF NON-VOLATILE SOLVENT IN 30 TO 70 PARTS OF A VOLATILE AROMATIC HYDROCARBON SOLVENT SELECTED FROM THE GROUP CONSISTING OF TOLUENE, BENZENE, AND XYLENE, (B) ADDING A HOT AQUEOUS SOLUTION OF BARIUM HYDROXIDE TO THE SOLUTION OF OIL-SOLUBLE SULFONIC ACID, SAID SOLUTION OF BARIUM HYDROXIDE CONTAINING FROM ABOUT 11/2 TO ABOUT 21/2 TIMES THE AMOUNT OF BARIUM HYDROXIDE REQUIRED TO REACT WITH THE SULFONIC ACID, (C) HEATING THE REACTION MIXTURE AT REFLUX TEMPERATURES, (D) REMOVING SUBSTANTIALLY ALL OF THE WATER BY AZEOTROPIC DISTILLATION WITH THE VOLATILE AROMATIC HYDROCARBON SOLVENT, (E) REMOVING ANY RESIDUAL VOLATILE AROMATIC SOLVENT BY DISTILLATION, (F) STRIPPING AND FILTERING THE PRODUCT. 